This invention relates to waterbeds of the type disclosed in U.S. Pat. No. 3,585,356 issued June 15, 1971 to Charles P. Hall and entitled LIQUID SUPPORT FOR HUMAN BODIES.
Ideally the user is supported in a comfortable position by a waterbed in such manner that the contact pressure is equalized and small. In order to minimize the contact pressure the area of contact is maximized. The ultimate limit is floatation independently of any stress in the bag itself. This theoretical limit is, in reality, not truly desirable. Thus true floatation would mean an inclined or other non-horizontal sleeping position due to the increased buoyancy of the chest cavity as compared with the lower limbs. True floatation would mean the body would tend to shift in the horizontal plane. To achieve a substantial degree of floatation, the water bag is peripherally confined so that much of the tension of the bag is relieved.
In practice, the bag tension is minimal when the bed is unoccupied. When one person rests upon the bag, the stress of body weight causes a slight tension in the bag which is unobjectionable, and perhaps desirable. But when a second person occupies the bed, the tension builds up to a point where floatation is largely lost, and bag tension serves as the primary support mechanism.
The primary object of the present invention is to provide a waterbed that automatically maintains floatation as the primary support mechanism notwithstanding substantial differences in the weight load imposed upon the waterbed.